Reciprocating tool

ABSTRACT

A reciprocating tool includes a motor, a reciprocating member, and a crank mechanism. The motor is disposed in a housing. The reciprocating member projects from the housing. The crank mechanism converts rotation of a rotation shaft of the motor into reciprocation of the reciprocating member. The crank mechanism rotates around an axis in a lateral direction by rotation transmission from the rotation shaft, and the crank mechanism includes a crank member having an eccentric pin, a connecting rod coupling the eccentric pin to the reciprocating member, and a balancer coupled to the eccentric pin, and the balancer is supported by the eccentric pin alone in the housing.

This application is a continuation of U.S. application Ser. No.15/045,609 filed Feb. 17, 2016, which is based on and claims priorityunder 35 U.S.C. 119 from Japanese Patent Application Numbers 2015-075254filed on Apr. 1, 2015 and 2015-075255 filed on Apr. 1, 2015. Thecontents of the above application are incorporated herein by reference.

BACKGROUND Technical Field

The present invention relates to a reciprocating tool such as areciprocating saw configured to cause a reciprocating member such as aslider to be reciprocated by a crank mechanism.

Related Art

A reciprocating tool includes a crank mechanism constituted of a crankmember such as a bevel gear to which rotation of a motor is transmitted,an eccentric pin disposed on an eccentric position of the crank member,and a connecting rod one end of which is coupled to the eccentric pin.The other end of the connecting rod is coupled to the reciprocatingmember to convert the rotation of the motor into reciprocation of thereciprocating member. For example, Japanese Patent ApplicationPublication 2014-24126 A discloses a reciprocating saw with a slider asthe reciprocating member mounting a cutting blade. Further, there hasbeen known a technique in which a balancer is pressed-in and fixed on adistal end of the eccentric pin for reduction of vibration.

Furthermore, as disclosed in Japanese Patent Application Publication2014-133284 A for example, a motor is housed in a cylindrical motorhousing constituted by assembling a pair of half housings.

In such reciprocating tool, the crank member is occasionally disposed invertical with an axis in the lateral direction with respect to thereciprocating member disposed in the front-rear direction. In thisvertical crank mechanism, the pin pressed-in and fixed on the rotationalcenter of the balancer is held by a bearing disposed on the innersurface of the housing. However, when the reciprocating member istemporarily locked by an excessive load in use, the impact generates adeviation in the positional relationship between the crank member andthe balancer. As a result, a deviation is also generated between thecenter of the bearing supporting the crank member and the center of thebearing supporting the pin of the balancer. Then, abnormal noise andabnormal vibration are generated between the crank mechanism and thehousing. On the other hand, employing a compact brushless motor as themotor ensures the reduced size (diameter) of the motor housing.Accordingly, in a case of a model such as a reciprocating saw thatgenerates the vibration, the motor housing with a half-split structuremay cause rigidity shortage.

Therefore, it is an object of the present invention to provide areciprocating tool that can reduce the generation of abnormal noise andabnormal vibration regardless of the impact in locking a reciprocatingmember.

It is also an object of the present invention to provide a reciprocatingtool that can ensure the rigidity of a motor housing even if a brushlessmotor is employed.

SUMMARY

In order to achieve the above-described object, a reciprocating toolaccording to a first aspect of the present invention includes a motor, areciprocating member, and a crank mechanism. The motor is disposed in ahousing. The reciprocating member projects from the housing. The crankmechanism converts rotation of a rotation shaft of the motor intoreciprocation of the reciprocating member. The crank mechanism rotatesaround an axis in the lateral direction by rotation transmission fromthe rotation shaft. The crank mechanism includes a crank member, aconnecting rod, and a balancer. The crank mechanism has an eccentricpin. The connecting rod couples the eccentric pin to the reciprocatingmember. The balancer is coupled to the eccentric pin. The balancer issupported by the eccentric pin alone in the housing.

A reciprocating tool according to a second aspect of the presentinvention, which is in the first aspect of the present invention, thebalancer is supported by pressing-in of the eccentric pin.

A reciprocating tool according to an eighth aspect of the presentinvention, which is in the first aspect of the present invention, themotor is a brushless motor where the rotation shaft extends in thefront-rear direction. The reciprocating tool further includes a tip endtool holder driven by the brushless motor, a motor housing of anintegrally molded cylinder type for housing the brushless motor, ahandle housing of a loop type coupled to the motor housing, and acontrol unit that is disposed on the lower portion of the handle housingand controls the brushless motor.

A reciprocating tool according to a ninth aspect of the presentinvention, which is in the first aspect of the present invention, themotor is a brushless motor where the rotation shaft extends in thefront-rear direction. The reciprocating tool further includes a tip endtool holder driven by the brushless motor, a motor housing of anintegrally molded cylinder type for housing the brushless motor, ahandle housing coupled to the motor housing, a battery mounting portionthat is disposed on the lower portion of the handle housing and mounts abattery, and a control unit that is disposed on the battery mountingportion and controls the brushless motor.

A reciprocating tool according to a tenth aspect of the presentinvention, which is in the first aspect of the present invention, themotor is a brushless motor where the rotation shaft extends in thefront-rear direction. The reciprocating tool further includes a tip endtool holder driven by the brushless motor, a first motor housing of anintegrally molded cylinder type for housing the brushless motor, asecond motor housing that covers the first motor housing, and a handlehousing integrally formed with the second motor housing.

A reciprocating tool according to an eleventh aspect of the presentinvention, which is in the first aspect of the present invention, themotor is a brushless motor where the rotation shaft extends in thefront-rear direction. The reciprocating tool further includes a tip endtool holder driven by the brushless motor, a motor housing of anintegrally molded cylinder type for housing the brushless motor, ahandle housing coupled to the motor housing, a control unit that isdisposed on the lower portion of the handle housing and controls thebrushless motor, an exhaust outlet disposed on the motor housing, and anair intake opening disposed on the handle housing.

With the reciprocating tool according to the embodiment disclosed in thefirst aspect of the present invention, the generation of the abnormalnoise and the abnormal vibration is reduced by supporting the balancerby the eccentric pin alone in the housing, regardless of the impact inlocking the reciprocating member.

With the reciprocating tool according to the embodiment disclosed in thesecond aspect of the present invention, in addition to the effect of thefirst aspect of the present invention, pressing-in of the eccentric pinensures the balancer to be mounted easily.

With the reciprocating tool according to the embodiment disclosed in theeighth to eleventh aspect of the present invention, in addition to theeffect of the first aspect of the present invention, employing the motorhousing of the integrally molded cylinder type ensures the rigidity evenif the brushless motor is employed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a rechargeable reciprocating saw.

FIG. 2 is a back view of the rechargeable reciprocating saw.

FIG. 3 is a plan view the rechargeable reciprocating saw.

FIG. 4 is a cross-sectional view taken along the line A-A of FIG. 1.

FIG. 5 is a partial cross-sectional view taken along the line B-B ofFIG. 3.

FIG. 6 is a vertical cross-sectional view of the rechargeablereciprocating saw.

FIG. 7 is a side view of the rechargeable reciprocating saw in a statewhere a left side half housing of a rear housing is omitted.

FIG. 8 is a perspective view of the rear housing part of FIG. 7.

FIG. 9 is an exploded perspective view of a brushless motor and an innermotor housing.

FIG. 10 is a vertical cross-sectional view of a front housing part.

FIG. 11 is a cross-sectional view taken along the line C-C of FIG. 10.

FIG. 12 is a cross-sectional view taken along the line D-D of FIG. 10.

FIG. 13 is an explanatory view illustrating a modification example of abattery mounting portion.

DETAILED DESCRIPTION

The following describes embodiments of the present invention based onthe drawings.

FIG. 1 is a side view of a rechargeable reciprocating saw (hereinaftersimply referred to as “reciprocating saw”) 1 as an exemplaryreciprocating tool. FIG. 2 is a back view, and FIG. 3 is a plan view ofthe reciprocating saw 1. A housing of the reciprocating saw 1 includes arear housing 2 that has a handle housing 3 and an outer motor housing 4as a second motor housing in the rear and front respectively, and afront housing 5 assembled ahead of the rear housing 2. The handlehousing 3 mounts a battery pack 6 as a power source on the lower end ofthe handle housing 3. The outer motor housing 4 houses a brushless motor7 (described later) inside as illustrated in FIG. 4 and FIG. 6. Thefront housing 5 houses a vertical crank mechanism 8 inside to convertrotation of the brushless motor 7 into reciprocation of a slider 9 as areciprocating member extending in the front-rear direction.

The rear housing 2 is made of resin and assembled with a pair of halfhousings 2 a and 2 b, which are integrally formed of the handle housing3 and the outer motor housing 4, by screws 10 in the lateral direction.The outer motor housing 4 is formed in a cylindrical shape that has alateral cross-sectional surface in an approximately oval shape. Thehandle housing 3 is formed of a handle upper portion 3 a, a handle lowerportion 3 b, a handle front portion 3 c, and a handle rear portion 3 din a loop shape projecting backward from the outer motor housing 4. Thehandle rear portion 3 d as a grip houses a switch 11 with a trigger 12projecting forward. A trigger signal line is coupled to a controller 33(described later) wired in the handle rear portion 3 d from the switch11. The handle upper portion 3 a includes a lock off button 13 capableof performing a sliding operation in the lateral direction, and includesa window 14 for displaying the position of the lock off button 13 on thetop surface of the handle upper portion 3 a. The handle front portion 3c, which closes the rear of the outer motor housing 4, includes aplurality of slit-shaped first air intake openings 15 on the right andleft sides in up and down direction. The handle lower portion 3 b alsoincludes second air intake openings 15 a on the right and left sides.

The outer motor housing 4 includes a depressed portion 16 on the upperright side. This depressed portion 16 supports a cylindrical hookreceiver 17 in the front-rear direction by fixing an extension plate 18disposed to extend on the left side to an inner motor housing 61(described later) by two screws 19 of front and rear as illustrated inFIG. 4. This hook receiver 17 mounts a suspension hook 20 formed of ametallic rod-shaped body folded in U-shaped. Specifically, a one endportion 20 a of the suspension hook 20 is inserted into the hookreceiver 17 from the rear, and a retaining pin 21 is passed through tothe distal end projecting from the hook receiver 17 orthogonally. Thisensures the suspension hook 20 to be mounted to retain. As illustratedin FIG. 5, the hook receiver 17 externally mounts a coil spring 24 onthe one end portion 20 a inside the hook receiver 17 between aprotrusion 22 disposed on the inner peripheral front side of the hookreceiver 17 and a stopper 23 externally mounted on the one end portion20 a in the rear of the protrusion 22. In the normal state, thesuspension hook 20 is biased on the retreated position where theretaining pin 21 is in contact with a locking ring 25 inserted into thefront end of the hook receiver 17. A projection 26 is disposed toprotrude on an outer periphery of the one end portion 20 a and receivesa rear end of the coil spring 24.

The locking ring 25 includes a cross-shaped groove 27 on the front facethereof, and the retaining pin 21 is locked on the groove 27 in thelateral direction and the vertical direction. As illustrated in FIG. 2by solid lines and two-dot chain lines, this ensures the suspension hook20 to be positioned on three positions where the retaining pin 21 islocked on the groove 27 (a housing position where an other end portion20 b of the suspension hook 20 comes to the lower side, a horizontallyprojecting position where the other end portion 20 b projects to theright side, an upward projecting position where the other end portion 20b projects upward) by 90°. When the position is changed, the suspensionhook 20 is extruded forward from the retreated position and the lockingof the retaining pin 21 with the locking ring 25 is released. Then, thesuspension hook 20 can be operated to rotate to any positions.

Accordingly, the reciprocating saw 1 can be suspended by locking theother end portion 20 b to a locking tool disposed on such as a wall orsimilar tool in a state where the suspension hook 20 is in the positionof the horizontally projecting position or the upward projectingposition. As illustrated in FIG. 1, the other end portion 20 b is bentat an acute angle such that the other end portion 20 b approaches theone end portion 20 a side as it goes forward. Therefore, the other endportion 20 b is hardly removed in a state where the other end portion 20b is locked to the locking tool or similar tool. A part near the otherend portion 20 b of the suspension hook 20 is configured to be bentinward along the side face of the outer motor housing 4 at the housingposition illustrated by the solid line in FIG. 2, so that the part doesnot project outside. As illustrated in FIG. 3, the whole suspension hook20 is within the maximum width of the reciprocating saw 1 at the housingposition without projecting. Furthermore, the suspension hook 20 at thehousing position surrounds the outside of a display area 28 for such asa company name logo, which is disposed on the side face of the outermotor housing 4, not to cover the display area 28.

The battery pack 6 is slid from forward to be mounted on a batterymounting portion 29 disposed on the lower end of the handle housing 3. Aretaining hook 30 is disposed on the battery pack 6 to lock the batterypack 6 on the battery mounting portion 29. A release button 31 releasesa lock state of the retaining hook 30.

As illustrated in FIG. 6 to FIG. 8, the battery mounting portion 29holds a terminal block 32 that is electrically coupled to the mountedbattery pack 6 in the front-rear direction inside the battery mountingportion 29. The battery mounting portion 29 holds the controller 33 as acontrol unit above the terminal block 32 inside the battery mountingportion 29. The controller 33 is held by a rib 34, which is disposed toprotrude on the inner surface of the handle housing 3, with some spacebetween the terminal block 32 and the controller 33, and parallel to theterminal block 32.

This controller 33 houses a switching element for controlling thebrushless motor 7 and a control circuit board 36 mounting amicrocomputer and similar device on a metallic dish-shaped case 35. Thecase 35 includes a grid-like groove 37 on the inferior surface toincrease an area contacted with air. From the rear top surface of thecontrol circuit board 36, lead wires 38 are extracted (in FIG. 7 andFIG. 8, illustrated by a simple one line) to wrap around the controller33 from the rear to downward. Then, the lead wires 38 pass through aspace between the terminal block 32 and the controller 33 to be pulledout forward, and are coupled to lead wires 59 and 60 (described below)pulled out from the brushless motor 7. Protective caps 39 are fitted ona coupling portion of the lead wire 38, and the lead wires 59 and 60. Adust-proof and water proof specification is realized by coating thecoupling portion of the lead wires one another including the protectivecap 39 by resin, so that an international standard IP56 is supported. Acapacitor 40 is not mounted on the control circuit board 36 butsupported by a support rib 41 above the controller 33 in the handlehousing 3 without obstructing the wiring of the lead wire 38. Thecapacitor 40 may be disposed on the handle front portion 3 c. Thus,space in the handle is effectively utilized by disposing the controlcircuit board on the lower portion of the loop-shaped handle anddisposing the capacitor on any of the handle rear portion or the handlefront portion to disperse electronic material components. This preventsthe handle from upsizing.

As illustrated in FIG. 4, FIG. 6, and FIG. 9, the brushless motor 7 isan inner rotor type motor including a stator 42 and a rotor 43 disposedinside the stator 42. First, the stator 42 has a cylindrical stator core44 formed of a plurality of laminating steel plates, a front insulator45 and a rear insulator 46 disposed on the end surfaces of the front andrear in the axial direction of the stator core 44 respectively, and sixcoils 47 wound around the stator core 44 via the front insulator 45 andthe rear insulator 46.

The rotor 43 includes a rotation shaft 48 disposed on the shaft center,an approximately cylindrically-shaped rotor core 49 disposed on theperipheral area of the rotation shaft 48 and formed of a plurality oflaminating steel plates, and four permanent magnets 50 inserted andfastened into the rotor core 49. On the rotation shaft 48, a centrifugalfan 51 is fastened ahead of the rotor core 49.

The front insulator 45 includes depressed relief portions 52 on thepoint symmetry position of the circumferential surface, and the rearinsulator 46 includes four cutouts 53 on the circumferential surface atregular intervals in the circumferential direction. Furthermore, therear insulator 46 holds six fusing terminals 54 on the rear face thatare performed fusing by a winding wire between the coil 47 and the coil47. On the rear face of the rear insulator 46, a sensor circuit board 55mounting three rotation detecting elements (not illustrated) fordetecting the position of the permanent magnet 50 to output a rotationdetecting signal, and a short-circuit member 56 including three sheetmetal members 57 for short-circuiting the fusing terminals 54 diagonallyone another are mounted by screws 58 from backward. The lead wire 59 iscoupled to the sensor circuit board 55 to output the rotation detectingsignal, and the lead wire 60 is coupled to each sheet metal member 57for a power source. The lead wires 59 and 60 are pulled out from theidentical phase (here, the lower left side) of the stator 42.

The brushless motor 7 is housed in the inner motor housing 61 as asecond motor housing that is secured to inside the outer motor housing4. The inner motor housing 61 includes a main body cylinder 62 with anopening on the front that houses the whole stator 42 and a part of therotor 43 (the rear part including the rotor core 49), and a closingplate 63 closing the opening of the main body cylinder 62. The innermotor housing 61 has a planar surface shape in the front-rear direction,and the type is an integrally molded cylinder type not divided laterallyor vertically.

The main body cylinder 62 includes a bearing holder 64 on the center ofthe rear portion to hold a bearing 65 pivotally supporting the rear endof the rotation shaft 48. The main body cylinder 62 opens suctionopenings 66 on the peripheral area of the bearing holder 64. The mainbody cylinder 62 includes anchor pieces 68 disposed to protrude on theupper and lower position of the outer periphery. Each of the anchorpieces 68 fits in right and left screw bosses 67 for assembling the halfhousings 2 a and 2 b, and has a through hole 69. In assembling the halfhousings 2 a and 2 b, the anchor pieces 68 are sandwiched by the rightand left screw bosses 67. This causes the main body cylinder 62 to befastened. The main body cylinder 62 includes an outlet 70 for the leadwires 59 and 60 drilled on the left side of the lower anchor piece 68 onthe inferior surface of the main body cylinder 62.

The main body cylinder 62 includes a pedestal 71 disposed to protrude onthe top surface that is consecutively installed on the upper anchorpiece 68 toward the front to make the top surface flat. This pedestal 71exposes to an opening 72 disposed on the bottom of the depressed portion16 of the rear housing 2 in a state where the pedestal 71 is assembledto the rear housing 2. On the pedestal 71, the extension plate 18 of thehook receiver 17 is screwed. In the pedestal 71, a metal plate 73 (FIG.4) to which the screws 19 are screwed is inserted and held. A throughhole 74 is disposed on the pedestal 71 at a screw position.

Furthermore, the main body cylinder 62 includes a flange portion 75 inthe front portion projecting out with a vertically elongated rectangularshape in front view. The flange portion 75 includes penetration holes 76on the four corners. The main body cylinder 62 includes a pair of screwreceiving portions 77 opening toward the front in a phase different fromthe upper and lower anchor pieces 68 on the outer periphery of the mainbody cylinder 62.

Additionally, the main body cylinder 62 includes peripheral ribs 78disposed upright on the circumferential surface along thecircumferential direction by a predetermined distance in back and forth.The flange portion 75 also includes upper ribs 79 disposed upright onthe top surface at the identical height with the pedestal 71 by apredetermined distance in back and forth. These peripheral rib 78 andupper rib 79 lock to inner ribs 80 disposed to protrude on the innersurface of the outer motor housing 4, as illustrated in FIG. 4. Thisrestricts the move in the front-rear direction.

Then, the main body cylinder 62 internally includes a plurality ofprotrusions 81 that are disposed in the axial direction to bring incontact with the outer periphery of the stator 42. The protrusions 81are disposed to protrude with a predetermined interval in thecircumferential direction. The main body cylinder 62 includes fourtriangular locking projections 82 on the bottom face inside the mainbody cylinder 62. The locking projections 82 correspond to the fourcutouts 53 disposed on the circumferential surface of the rear insulator46. The main body cylinder 62 includes chamfering portions 83 on theright and left side faces in the front portion.

The closing plate 63 is ring-shaped having a center hole 84 throughwhich the rotor core 49 of the rotor 43 passes. The closing plate 63includes chamfering portions 85 on the right and left outer surfacescorresponding to the chamfering portions 83 of the main body cylinder62. The closing plate 63 includes a pair of cylindrical portions 86 onthe outer periphery disposed toward the rear at the positioncorresponding to the screw receiving portions 77 of the main bodycylinder 62. Each cylindrical portion 86 integrally includes a presserboss 87 with a penetration hole internally on the rear end. The presserboss 87 is used for screwing the closing plate 63. The presser boss 87is in contact with the front face of the stator core 44 at the positionof the depressed relief portion 52 of the front insulator 45 to pressthe stator 42 on the rear inner surface of the main body cylinder 62.

Then, in a state where the lead wires 59 and 60 are precedingly passedthrough the outlet 70, the stator 42 is inserted into the main bodycylinder 62 from the front in the phase where the depressed reliefportions 52 are adjusted to the screw receiving portions 77. Thisensures the stator 42 to be held coaxially by the protrusions 81 in themain body cylinder 62. Each locking projection 82 locked on each cutout53 is brought in contact with the rear face of the stator core 44 todecide the push-in position. Simultaneously, locking of each lockingprojection 82 on each cutout 53 ensures to stop the rotation.

Next, the closing plate 63 is fitted to the opening of the main bodycylinder 62 with adjusting the position of the chamfering portions 85 ofthe closing plate 63 to the chamfering portions 83 of the main bodycylinder 62 side. Then, the presser bosses 87 are in contact with thefront face of the stator core 44 at the position of the depressed reliefportions 52. Then, a pair of screws 88 is inserted into the presserbosses 87 from the front to screw to the screw receiving portions 77 ofthe main body cylinder 62. This ensures the stator 42 to be housed inthe inner motor housing 61.

Then, the rotor 43 mounting the bearing 65 on the rear end of therotation shaft 48 is inserted into the inner motor housing 61 from thecenter hole 84 of the closing plate 63 to cause the bearing holder 64 tohold the bearing 65. This ensures the rotor 43 to be housed in the innermotor housing 61 except a part ahead of the centrifugal fan 51. Ahead ofthe centrifugal fan 51 on the rotation shaft 48, a bearing 89 ismounted, and between the bearing 89 and the centrifugal fan 51, astopper plate 90 through which the rotation shaft 48 passes is disposedincluding cuts 91, 91 on the upper and lower ends. The rotation shaft 48includes a pinion 92 on the distal end.

As illustrated in FIG. 10 to FIG. 12, the front housing 5 is made ofmetal assembling a left split mold 5 a and a right split mold 5 b byscrews 93 in the lateral direction. The left split mold 5 a includes asmall cylindrical holder 94 for holding the bearing 89 of the rotationshaft 48. The front housing 5 includes screw holes 95 (FIG. 6) upper andlower on the rear face corresponding to the cuts 91 of the stopper plate90. The front housing 5 includes four screw bosses 96 on the rear facedisposed to protrude corresponding to the four penetration holes 76 ofthe flange portion 75 disposed on the main body cylinder 62. Then, in astate where the distal end of the rotation shaft 48 passes through theholder 94 and the bearing 89 fits the holder 94, the flange portion 75of the inner motor housing 61 is placed on the rear face of the fronthousing 5, and four screws 97 (FIG. 4, FIG. 7, and FIG. 8) are screwedinto the screw bosses 96 from the rear via the penetration holes 76.Then, when screws 98 are screwed into the screw holes 95 via the cuts 91of the stopper plate 90, the inner motor housing 61 is coupled to therear end of the front housing 5 to cause the pinion 92 of the rotationshaft 48 to project inside the front housing 5. In this state, thebearing 89 is prevented from coming off from the holder 94 by thestopper plate 90.

Then, the inner motor housing 61 is set on the left side half housing 2a and the anchor pieces 68 are placed on the screw bosses 67. At thesame time, the controller 33, the switch 11, and similar units areassembled, the lead wire 38 is coupled to the lead wires 59 and 60 oneanother, and similar operations are performed to complete the wiring. Inthis state, the left side half housing 2 a is covered with and screwedto the right side half housing 2 b with the screws 10, so that the rearhousing 2 is coupled to the front housing 5 via the inner motor housing61. Exhaust outlets 99 (FIG. 1) opens outside the centrifugal fan 51 onthe right and left sides of the forward end portion of the outer motorhousing 4.

On the other hand, the left split mold 5 a and the right split mold 5 bof the front housing 5 includes depressed housing portions 100 and 101respectively for housing the vertical crank mechanism 8 and the slider9. The left split mold 5 a and the right split mold 5 b sandwich asealing member 102 on the assembling surface except the part where theslider 9 passes through. The left split mold 5 a has a large left andright width compared with the right split mold 5 b, and the depressedhousing portion 100 has a large depth compared with the depressedhousing portion 101. This causes the assembling surface of the leftsplit mold 5 a and the right split mold 5 b to be shifted to the rightside of the center in the lateral direction.

The vertical crank mechanism 8 includes a bevel gear 103 as a crankmember to which the pinion 92 of the rotation shaft 48 engages, aneccentric pin 104 disposed to protrude on the eccentric position of thebevel gear 103, a balancer 105 secured to the distal end of theeccentric pin 104, and a band plate-shaped connecting rod 106 coupled tobetween the eccentric pin 104 and the rear end of the slider 9. Here,the bevel gear 103 is disposed vertically such that a support shaft 107in the lateral direction, which is screwed orthogonally in the depressedhousing portion 100 of the left split mold 5 a to project inward,supports the bevel gear 103 rotatably via a bearing (needle bearing)108. A washer 109 retains the bevel gear 103, and a bolt 110 secures thewasher 109 to the distal end of the support shaft 107.

The balancer 105 includes a weight portion 111 in fan-shape in sideview, and a projecting portion 112 projecting from the center of theweight portion. The projecting portion 112 has a press-in hole 113 onthe distal end. By pressing-in the distal end of the eccentric pin 104to the press-in hole 113, the balancer 105 is rotatable integrally withthe eccentric pin 104. A through hole 114 is drilled on the boundarypart of the weight portion 111 and the projecting portion 112, on theextended line of the bolt 110. The through hole 114 ensure a tool to beinserted for rotating operation of the bolt 110 even if the balancer 105is fixed. A positioning hole 115 is disposed on the weight portion 111used for the positioning in fixing the balancer 105. The rear end of theconnecting rod 106 is coupled to the eccentric pin 104 between the bevelgear 103 and the balancer 105, and on the approximately center positionin the lateral direction. Thus, the balancer 105 is supported by theeccentric pin 104 alone, and has a structure without the support by theright split mold 5 b.

Then, the slider 9 is held slidably in the front-rear direction ahead ofthe bevel gear 103 and on the upper position of the rotational center ofthe bevel gear 103 by a holder 116, which is held by the left and rightsplit molds 5 a and 5 b. This holder 116 includes a pair of U-shapedbrackets 118 secured in a depressed groove 117 that is disposed in thefront-rear direction on the inner surface of the left split mold 5 a andthe right split mold 5 b. Each of the brackets 118 is secured to thedepressed grooves 117 of the left and right split mold 5 a and 5 b. Onthe upper and lower sides of each bracket 118, an upper flange 119 thatis short in the back and forth direction and a lower flange 120 that islong in the back and forth direction are bent to be formed. Each of theupper and lower flanges 119 and 120 include a pair of through holes 121in the back and forth direction.

On each inner surface of the left and right split molds 5 a and 5 b, apin 122 is driven on the position corresponding to the through hole 121disposed on the upper side of the depressed groove 117 and the frontside of the upper flange 119, and a screw hole 123 is disposed on theposition corresponding to the rear side through hole 121. On the otherhand, on the position corresponding to the through hole 121 disposed onthe lower side of the depressed groove 117 and the front side of thelower flange 120, the screw hole 123 is disposed, and on the positioncorresponding to the rear side through hole 121, the pin 122 is driven.Accordingly, by inserting the pin 122 into one through hole 121 of theupper and lower flanges 119 and 120, and screwing a bolt 124 into thescrew hole 123 from the other through hole 121, each bracket 118 isfastened in the depressed groove 117.

The front end of the connecting rod 106 is coupled to the slider 9 inthe following manner. In a state where the front end of the connectingrod 106 is placed between legs of a bifurcated portion 125 disposed onthe rear end of the slider 9, a coupling pin 126 is passed throughacross the bifurcated portion 125 and the connecting rod 106 in thelateral direction. On both ends of the coupling pin 126, deflectors 127,127 that fit to the brackets 118, 118 engage. In accordance with thesliding of the deflectors 127, 127 on both ends along the bracket 118,the slider 9 is held by a slider guide 140, the front portion of whichis disposed in the front housing 5, so that the slider is guided toslide in the front-rear direction. The slider 9 includes a blade holder128 as a tip end tool holder that mounts a blade (not illustrated) onthe front end projecting from the front housing 5.

On the other hand, the front housing 5 includes a guide shoe 129 belowthe slider 9 inside the front housing 5. This guide shoe 129 includes aslide bar 130 mounted slidable in the front-rear direction, and a shoe131 secured on the front end of the slide bar 130 perpendicular to theslide bar 130 and through which the blade mounted on the blade holder128 passes. In the front housing 5, a coil spring 132 downwardly biasesa locking plate 133, and any of a plurality of locking depressedportions 134 disposed on the top surface of the slide bar 130 isselected to lock the locking plate 133. This ensures the front and rearpositions of the shoe 131 to be adjusted. The positioned slide bar 130is locked by the operation of a locking shaft 130 a disposed ahead ofthe locking plate 133.

A LED 135 is disposed on the front face upper portion of the fronthousing 5 for lighting, and electrically coupled to the controller 33 inthe rear housing 2 side by a lead wire (not illustrated) wired in a longgroove 136 disposed on the left split mold 5 a above the depressedhousing portion 100 in the front-rear direction. On the outer peripheryof the front housing 5, a cylindrical rubber cover 137 is externallymounted from the front. The rubber cover 137 is disposed to extend tothe position where the rear end of the rubber cover 137 covers the frontend of the outer motor housing 4 of the rear housing 2, and covers apart of the exhaust outlets 99, 99 except the central portion of theleft and right side surfaces. However, the rubber cover 137 includesabutting ribs 138 disposed upright on the inner surface to abut on theouter surface of the front housing 5 in the front-rear direction. Theabutting ribs 138 form ventilation passages 139 inside the rubber cover137 such that the air discharged from the exhaust outlet 99 passesbetween the rubber cover 137 and the front housing 5 to dischargeforward.

According to the reciprocating saw 1 configured as described above,pushing the trigger 12 to turn the switch 11 to ON causes the brushlessmotor 7 to drive by the power supply of the battery pack 6. That is, themicrocomputer of the control circuit board 36 acquires the rotationdetecting signal that is output from the rotation detecting element ofthe sensor circuit board 55 and indicates the position of the permanentmagnet 50 of the rotor 43 to obtain the rotating state of the rotor 43.Then, the microcomputer controls ON/OFF of each switching elementcorresponding to the obtained rotating state, and supplies the currentto each coil 47 of the stator 42 in order. This causes the rotor 43 torotate.

Subsequently, the rotation shaft 48 rotates to cause the bevel gear 103to rotate, and the eccentric pin 104 moves eccentrically. This causesthe slider 9 to reciprocate via the connecting rod 106, and ensures thecutting of the cut material by the mounted blade. At this time, inaccordance with the reciprocation of the slider 9, the balancer 105reversely rotates in the back and forth direction with respect to therotational center of the bevel gear 103. This reduces the generation ofthe vibration.

Here, if an excessive load applied to the blade during the cuttingoperation temporarily locks the slider 9, the impact generates adeviation in the positional relationship of the bevel gear 103 and thebalancer 105. However, the balancer 105 is cantilevered by the eccentricpin 104 alone of the left split mold 5 a without the support by theright split mold 5 b. This reduces the deviation between the bevel gear103 and the balancer 105. Accordingly, the influence to the fronthousing 5 is reduced, and the abnormal noise and the abnormal vibrationare less likely to be generated.

On the other hand, the rotation of the centrifugal fan 51 with therotation shaft 48 causes the outside air to be suctioned from the firstair intake opening 15 and the second air intake opening 15 a of thehandle housing 3. Then, the suctioned outside air flows into the mainbody cylinder 62 from the suction opening 66 of the inner motor housing61. Then, after the air flown into the main body cylinder 62 passesthrough between the coil 47 and the coil 47 inside the stator 42, andbetween the stator 42 and the inner surface of the main body cylinder 62outside the stator 42, the air is introduced to the center hole 84 ofthe closing plate 63, and radially sent from the centrifugal fan 51 tobe discharged from the exhaust outlet 99. Thus, the closing plate 63functions as a baffle plate. This airflow cools the brushless motor 7.The air flown into from the second air intake opening 15 a passes thecontroller 33 to flow to the brushless motor 7. This ensures to cool thecontroller 33. A part of the air discharged from the exhaust outlet 99is discharged forward passing through the ventilation passage 139 in therubber cover 137 as described above. This ensures to cool the fronthousing 5.

Thus, according to the reciprocating saw 1 of the above-describedconfiguration, by supporting the balancer 105 by the eccentric pin 104alone in the front housing 5, the generation of the abnormal noise andthe abnormal vibration is reduced regardless of the impact in lockingthe slider 9.

In the present invention, especially, the balancer 105 is supported bypressing-in of the eccentric pin 104. This makes the mounting of thebalancer 105 easy.

According to the reciprocating saw 1 of the above-describedconfiguration, the configuration including the inner motor housing 61 ofthe integrally molded cylinder type for housing the brushless motor 7,the outer motor housing 4 for covering the inner motor housing 61, andthe handle housing 3 integrally formed with the outer motor housing 4ensures the rigidity even if the brushless motor 7 is employed.Furthermore, the outer motor housing 4 coupled to the inner motorhousing 61 provides the wide display space (display area 28) for such asthe company name logo.

Especially, since the outlet 70 for the wiring is disposed on the mainbody cylinder 62, the wiring to the controller 33 is easy even if theinner motor housing 61 of the integrally molded cylinder type isemployed.

Mounting the balancer is not limited to pressing-in. The balancer may bemounted by the combination of the rotation stopper by such as a keycoupling and a retaining by a pin. The shape of the balancer itself maybe changed as necessary. The crank member includes a member integrallycoupling a bevel gear to a crankshaft having an eccentric pin except amember having a bevel gear on which an eccentric pin is directlydisposed.

The holder of the slider can be formed by combining a pair of L-shapedbrackets other than forming by combining a pair of U-shaped brackets asdescribed above.

However, other than supporting the balancer by the eccentric pin alone,the eccentric pin configured to be loosely inserted with respect to thebalancer can reduce the impact even if the configuration where the pinpressed-in and fixed on the rotational center of the balancer is held bythe bearing disposed on the inner surface of the housing conventionally.

Furthermore, the first motor housing for housing the brushless motor maybe formed by coupling a plurality of cylinders divided by the surfaceperpendicular to the axial direction, not limited to the configurationof the motor housing where the closing plate is mounted on the main bodycylinder as described above. The arrangement of the first motor housingmay be arranged in the oblique direction, the upward direction, thedownward direction and similar direction corresponding to the type ofthe power tool and the form of the housing other than the arrangement inthe forward direction where the rotation shaft extends in the front-reardirection. The first air intake opening may be removed, or the secondair intake opening may be removed if the heat generation of the controlcircuit board is low.

Otherwise, as illustrated in FIG. 13 for example, the configurationwhere a pair of terminal blocks 32 are disposed in sideways in back andforth on the battery mounting portion 29 to mount two battery packs 6, 6may be employed.

Then, in the embodiment where the second motor housing covers the firstmotor housing and the embodiment where the control unit and the batterymounting portion are disposed on the lower portion of the handlehousing, these embodiments can be adopted to the power tool such as ascrew driver, an electric drill, a hammer drill and similar power toolnot limited to the reciprocating saw. An AC tool without the batterypack as the power source may be employed.

It is explicitly stated that all features disclosed in the descriptionand/or the claims are intended to be disclosed separately andindependently from each other for the purpose of original disclosure aswell as for the purpose of restricting the claimed invention independentof the composition of the features in the embodiments and/or the claims.It is explicitly stated that all value ranges or indications of groupsof entities disclose every possible intermediate value or intermediateentity for the purpose of original disclosure as well as for the purposeof restricting the claimed invention, in particular as limits of valueranges.

What is claimed is:
 1. An electric power tool having a front end and arear end, the electric power tool comprising: a tool holding portion atthe front end, the tool holding portion configured to hold a removabletool; a brushless motor having a stator and a rotor inside of thestator, the rotor being configured to drive the tool holding portion; aninner motor housing enclosing the brushless motor; an outer tool housingcomprising: a motor housing region surrounding the inner motor housing;and a loop shaped handle at the rear end of the power tool, the loopshaped handle configured with outer air intake openings configured tofeed cooling air to the brushless motor; a fan located at a front sideof the rotor; and a plate located at a front side of the stator and arear side of the fan; wherein the plate is attached to the inner motorhousing.
 2. The electric power tool of claim 1, wherein: a lower portionof the loop shaped handle is configured for attachment of a removablebattery; the loop shaped handle is (1) clam-shaped and (2) comprised oftwo pieces with abutting edges along a plane parallel to a longitudinalaxis of the electric power tool; the inner motor housing has a throughhole; and the two pieces are attached by a fastener extending throughthe through hole.
 3. The electric power tool of claim 2, wherein theinner motor housing further comprises inner air intake openings orientedat a proximal end of the inner motor housing and configured to feedcooling air from the outer intake openings to a central region of thebrushless motor.
 4. The electric power tool of claim 3, furthercomprising: a sensor circuit board configured to determine a rotatingstate of a rotor of the brushless motor, the sensor circuit boardoriented at a rear end of the brushless motor within the inner motorhousing; a control circuit board configured to control operation of thebrushless motor based on input from the sensor circuit board, thecontrol circuit board oriented in a lower region of the loop shapedhandle; and a capacitor oriented within the loop shaped handle separatefrom the control circuit board.
 5. The electric power tool of claim 4,further comprising: an LED located at the rear end of the power tool,the LED connected to the control circuit board by way of an LED wirecoupling, the LED wire coupling being located within the loop shapedhandle.
 6. The electric power tool of claim 3, wherein the inner motorhousing being cup-shaped and not separable along a plane parallel to thelongitudinal axis of the power tool, the inner motor housing having anopening at a distal end of the inner motor housing and configured to beclosed by a closing plate so as to enclose the brushless motor withinthe inner motor housing.
 7. A reciprocating saw configured with aproximal holding end and a distal working end, the reciprocating sawelectric power tool comprising: a tool holding portion arranged at thedistal working end, the tool holding portion configured to hold aremovable tool; a brushless motor having a rotational axis andconfigured to drive the tool holding portion; a fan coaxial with therotational axis of the brushless motor and disposed at a distal end ofthe brushless motor; a cup-shaped inner motor housing not separablealong a plane parallel to a longitudinal axis of the power tool, thecup-shaped inner motor housing having an opening toward a distal end ofthe inner motor housing, the inner motor housing comprising: inner airintake openings oriented at a proximal end of the cup-shaped inner motorhousing and configured to feed cooling air to a central region of thebrushless motor, and a closing plate disposed at the distal end of theinner motor housing and configure to cover the opening at the distal endof the inner motor housing so as to enclose the brushless motor withinthe inner motor housing, the closing plate having a central exhaustopening aligned with the rotational axis of the brushless motor; and aclam-shaped outer tool housing, the outer tool housing being separablein two pieces along a plane parallel to the longitudinal axis of thepower tool, the outer tool housing comprising: a motor housing regionsurrounding the inner motor housing; and a loop shaped handle at theproximal end of the power tool, the loop shaped handle comprising: outerair intake openings configured to feed cooling air to the inner airintake openings, and a lower portion configured for attachment of aremovable battery.
 8. The reciprocating saw electric power tool of claim7, further comprising: a sensor circuit board configured to determine arotating state of a rotor of the brushless motor, the sensor circuitboard oriented at a proximal end of the brushless motor within the innermotor housing; a control circuit board configured to control operationof the brushless motor based on input from the sensor circuit board, thecontrol circuit board oriented in a lower region of the loop shapedhandle; and a capacitor removed from the control circuit board andoriented within the loop shaped handle.
 9. The reciprocating sawelectric power tool of claim 8, further comprising: an LED located atthe distal working end of the power tool, the LED connected to thecontrol circuit board by way of a LED wire coupling, the LED wirecoupling being located within the loop shaped handle.
 10. An electricpower tool having a front end and a distal rear end, the electric powertool comprising: a tool holding portion at the front end, the toolholding portion configured to hold a removable tool; a brushless motorhaving a stator and a rotor inside of the stator, the rotor configuredto drive the tool holding portion; an inner motor housing enclosing thebrushless motor; and a loop shaped handle at the rear end of the powertool, the loop shaped handle configured with outer air intake openingsconfigured to feed cooling air to the brushless motor; wherein: theinner motor housing has an upper through hole and a lower through hole;the loop shaped handle is (1) clam-shaped and (2) comprised of twopieces with abutting edges parallel to a longitudinal axis of the powertool; and the two pieces are attached by fasteners extending through theupper through hole and the lower through hole.